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Viewing results 10 - 20 of 251 matches for "P" Back   |   Next
packless valve
valve that does not use packing to seal against leaks around the stem (e.g., bellows valve).
palladium cells
found in large, direct-fired and small, indirect-fired machines that continuously remove the small amount of hydrogen gas that is produced by corrosion.
panel cooler
refrigerated flat surface.
paraffinic oil
a petroleum lubricating oil fraction in which straight and/or branched-chain hydrocarbon structures predominate.
parallax
an inaccurate reading of a meter due to line of vision between the scale and the indicator being misaligned or angled.
parallel fan-powered VAV box
terminal device that combines a true VAV box in parallel with a fan and optional heating coils. Fan operation is intermittent.
parallel-flow heat exchanger
heat exchanger in which fluids flow approximately parallel to each other and in the same direction.
parallel-flow heat transfer
directional pattern of heat transfer fluids used in energy exchange equipment where the warmest fluid “A” indirectly contacts the coldest fluid “B” at the entering side of the exchanger.
partial pressure
(1) partial pressure of component i for any (ideal or nonideal) gas mixture is the product of the mole fraction of the component, xi, and the mixture pressure, p. [ pi ≡ xi • p for any gas mixture]. (2) portion of total gas pressure of a mixture attributable to one component (Dalton’s law of gases).
partially halogenated chlorofluorocarbon
a chlorofluorocarbon in which hydrogen atoms exists in the compound with chlorine and fluorine atoms. Partially halogenated chlorofluorocarbons are not expected to have high ozone depleting potential (ODP). Average atmospheric lifetime is about 2 years for HCFC 21 and 13 to 25 years for HCFC 22. Compare to halogenated chlorofluorocarbon.
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About ASHRAE Terminology

ASHRAE Terminology, a free resource, is a comprehensive online glossary of more than 3700 terms and definitions related to the built environment, with a focus on heating, ventilating, and air conditioning (HVAC), as well as refrigeration, building envelope, electrical, lighting, water and energy use, and measurement terms.

This searchable glossary was designed for use by engineering professionals but is also useful for architects, building owners and operators, educators, public officials, and homeowners.

The terms in ASHRAE Terminology have been assembled and defined and are updated on an ongoing basis by ASHRAE Technical Committee (TC) 1.6, Terminology. TC 1.6 is concerned with terminology, nomenclature, definitions, abbreviations, symbols, and the International System (SI) and Inch-Pound (I-P) units used in the fields of heating, ventilating, air conditioning, water heating, and refrigeration.

To request a free electronic file of the complete list of terms and definitions, email ashraetermseditor@ashrae.org.